The present invention relates generally to the control of aquatic weeds, and in particular to granulated aquatic herbicide compositions and their use in the control of aquatic weeds.
As further background, various methods exist for the control of aquatic weeds. The selection of an appropriate control method depends upon many factors such as environmental impact, cost effectiveness, efficacy, and the like. The various control methods available include physical controls such as mechanical harvesting, hand pulling or cutting, or the use of bottom barriers or water level draw-down. These methods can be both time consuming and labor intensive, and can create significant environmental disturbance, especially when considered on a large scale.
Biological controls such as the use of triploid grass carp can be desirable in some aquatic systems in that they reduce the use of equipment and have the potential for long term control of aquatic weeds. Nonetheless, in many aquatic systems, triploid grass carp often completely remove all aquatic vegetation for many years. The long-term environmental impacts result in reluctance of many natural resource managers to use triploid grass carp for these purposes. In temperate aquatic systems, the efficacy of such biological controls can also vary widely, and is dependent upon factors such as feeding preferences, metabolism, temperature, and stocking rate.
For these and other related reasons, the use of aquatic herbicides has become a common method for controlling invasive aquatic weeds. The use of herbicidal control nonetheless also presents risks and difficulties including the potential impact on the local environment, maintaining duration of herbicide exposure to control weeds in flowing water, selectivity to non-target species, the potential for excessive decrease in the dissolved oxygen (DO) content of the waters due to rapid plant decay, and possible toxicity to other life-forms.
In view of the background in this area, there are needs for improved and/or alternative aquatic herbicide formulations, and methods for their preparation and use. The present invention is addressed to these needs.